Fixes bevyengine#12000: When Viewport is set to Camera and switched t…

…o SizedFullscreen, panic may occur

When ajusting to SizedFullscreen, the window size might be lower than the viewport size, causing the render
target to be smaller than the Viewport. The fix consist of matching the viewport size with the render target
size when this is lower, avoiding panic. These lower values may vary depending on the device.

crates/bevy_render/src/camera/camera.rs

@@ -755,6 +755,17 @@ pub fn camera_system<T: CameraProjection + Component>(
                         }
                     }
                 }
+                if let Some(viewport) = &mut camera.viewport {
+                    let target_info = &new_computed_target_info;
+                    if let Some(target) = target_info {
+                        if viewport.physical_size.x > target.physical_size.x {
+                            viewport.physical_size.x = target.physical_size.x;
+                        }
+                        if viewport.physical_size.y > target.physical_size.y {
+                            viewport.physical_size.y = target.physical_size.y;
+                        }
+                    }
+                }
                 camera.computed.target_info = new_computed_target_info;
                 if let Some(size) = camera.logical_viewport_size() {
                     camera_projection.update(size.x, size.y);